<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8" />
    <title>Document</title>
</head>
<body>
    <script type="text/javascript">
        function sum(a){
            return (b) => {
                return (c) => {
                    return a+b+c
                }
            }
        }
        console.log(sum(1)(2)(3)) 
    </script>
</body>
</html>